This invention relates to pouched laundry products which contain fabric softener particles for through-the-wash and dryer use.
Pouched Fabric Softener Laundry Products
When, for example, loose through-the-wash-and-rinse fabric softener particles are added to the wash step of a laundering process, it is inevitable that some of the particles will not adhere to or become trapped in the folds of the fabrics and will, therefore, be lost in the discarded wash solution or rinse water. In order to avoid such loss, the softener particles can be added to the wash solution in a sealed, porous water-insoluble pouch such as the types described in U.S. Pat. Nos. 4,571,924, Bahrani, issued Feb. 25, 1986, and 4,223,029, Mahler et al., issued Sept. 16, 1980, both incorporated herein by reference. Detergent granules are usually included in the pouch with the softener particles. When the pouch is placed in water in the wash step of the laundering process, the detergent dissolves, but the softener particles remain in the pouch through the wash and rinse. When the pouch is tumbled with the fabrics in the dryer, the softener particles melt onto the pouch material and the softener is transferred from the pouch material to the fabrics as the pouch comes into contact with the fabrics during the drying cycle.
Softener staining is an insidious problem in the art of dryer-added fabric softeners. This problem in pouched through-the-wash and dryer products with loose softener particles is even more so. The present invention is designed to reduce or substantially eliminate the softener staining problem in such products.
Various solutions to such softener staining have been proposed in the art. U.S. Pat. No. 4,113,630, Hagner et al., issued Sept. 12, 1978, discloses a through-the-wash laundry article utilizing a water-insoluble substrate in which laundry actives are enclosed and the fabric softener is in the form of immobilized softener dots raised above the surface of the substrate. U.S. Pat. No. 4,108,600, Wong, issued Aug. 22, 1978, discloses a pouched laminated through-the-wash laundry product having an additional wall placed in between the walls of the pouch to split it in two. Into one half is placed specially coated fabric softener particles and an electrolyte/pH control agent is placed in the other half. Wong uses in his example a plain polyester non-woven ply material as the inner wall material.
Other references of interest are the pouched laundry articles in general. GB patent specification No. 1,298,454, Atkins, published Dec. 6, 1972, discloses a packaged washing powder in a water-permeable bag. The bag contains a thermal plastic, discontinuous surface coating apparently for "heat sealing." Fabric softener particles are not mentioned in GB No. 1,298,454. U.S. Pat. No. 4,348,293, Clarke et al., issued Sept. 7, 1982, discloses a water-insoluble, water-permeable bag having a water-soluble or water-dispersible protective layer and containing a particulate detergent composition. U.S. Pat. No. 4,410,441, Davis et al., issued Oct. 18, 1983, discloses laminating two different materials into two large pouches. Typically, dry powders are laminated between a water-permeable substrate and a water-impermeable substrate. U.S. Pat. Nos. 4,259,383, Eggensperger et al., issued Mar. 31, 1981; 4,433,783, Dickinson, issued Feb. 28, 1984; and EPA 66,463, Haq (Unilever NV), Dec. 8, 1982, all incorporated herein by reference, are also background references.
Preferred pouch structures are multi-pouch porous sheet structures such as described in U.S. Pat. Nos. 4,571,924, supra; 4,638,907, Bedenk et al., issued Jan. 27, 1987; and 4,259,383, supra; all incorporated herein by reference. In a single pouch structure, the softener particles tend to collect in a relatively small area of the structure, whereas in a multi-pouch sheet structure the softener particles are distributed over a larger area of the structure thereby facilitating more even transfer of softener to fabrics in the dryer.
Selected fibrous substrates improve the release of fabric softener in a pouched granular detergent/softener product form over one made with an all cellulosic paper substrate.